Band tensioning tool



April 28, 1970 B. s. PALMER 3,

BAND TENSIONING TOOL Filed Sept. 14, 1967 2 Sheets-Sheet 2 IN VEN TORUnited States Patent 3,508,740 BAND TENSIONING TOOL Basil StoddardPalmer, 22 East St., Titchfield, Fareham, Hampshire, England Filed Sept.14, 1967, Ser. No. 667,724 Claims priority, application Great Britain,Oct. 27, 1966, 48,186/ 66 Int. fl. B21f 45/18; B66f 19/00 US. Cl. 254 7Claims ABSTRACT OF THE DISCLOSURE It is an object of the invention toprovide an improved device for tensioning the banding wire, making useof pneumatic or hydraulic power. Another object of the invention is toprovide means whereby the degree of ten- SlOl'l applied to the band orwire may be preset. The improved device operates in conjunction with aclip forming an anchorage for one end of the band or wire to betensioned along the article to be banded, while the free end of the bandor wire passes through the clip and is clamped to the banding device,the tension being produced by relative displacement of the clip andclamp.

Broadly, the invention consists in a device for tensioning a band orwire, comprising a housing in which a piston is movably disposed, meansbeing provided for subjecting the piston to hydraulic or pneumaticpower, the piston being arranged for displacing a carrier of a wire orband gripping member, the piston also being arranged for actuating thewire or band gripping member into gripping engagement with the wire orband, the arrangement being such that the wire or band gripping memberis actuated by the piston prior to movement of the said carrier by thepiston.

In order to make the invention clearly understood, reference will now bemade to the accompanying drawings which are given by way of example andin which:

FIG. 1 is a sectional view of a banding device of the invention, shownin engagement with a band;

FIG. 2 is a sectional view along the line IIII of FIG. 1; and

FIG. 3 is a sectional view along the line IIIIII of FIG. 1.

The banding device comprises a housing having a body portion 1 and anend portion 2. These portions are secured together by a tie rod 5 andscrews 22. On the tie rod 5, a piston 3 is movably guided, the pistonhaving an O-ring seal 29 which engages the cylindrical surface of thetie rod 5, and a cup-seal 28 which engages the surface of a cylindricalbore in the body portion 1 of the housing.

The banding device is intended to grip the free end of banding material34 which extends around an article to be banded, the other end of thebanding material 34 being fixed to a clip 33 through which the free endof the banding material 34 is to be drawn by the banding device.Accordingly, a pusher plate 13 fixed by screws 21 to the body portion 1of the housing is provided for engaging the clip 33. Slots 35 areprovided in the housing for passage of the banding material 34therethrough. For engaging the free end of the banding material 34 andapplying a tractive force there'o, a gripping arrangement is provided.This comprises an involute cam or pawl 6 which is mounted by a pivot pin9 in a carrier 4 which is movably guided on the tie rod 5. The pawl 6 isretained on the pivot pin 9 by a spring clip 26. The carrier 4 isadditionally guided on a rod 20 which extends between the portions 1 and2 of the housing.

The piston 3 is urged in the direction away from the end cap portion ofthe housing by springs 18 which are mounted on guides 11. The portion 1of the housing has an abutment surface 3 so positioned that it acts as astop for an abutment surface 37 of the pawl carrier 4 when the piston 3is moved towards its left hand end position, engagement between thesurfaces 36 and 37 taking place shortly before the piston reaches itsleft hand end position, for example A5 of an inch before.

A spring 19 mounted on a spigot 12 extending from the carrier 4 isprovided which tends to draw the piston 3 towards the carrier 4, butthis tendency is resisted by the springs 18 which are stronger than thesprings 19.

The piston 3 is fitted with an axially extending connecting rod 7, whichis secured thereto by means of a grub screw 23. The connecting rod 7 islinked to the pawl 6 by means of a pin 8 so that if the piston 3 isaxially moved from its left hand end position as viewed in FIG. 1, themovement of the connecting rod 7 will cause the pawl 6 to rotate aboutthe pivot pin 9, in the clockwise direction as viewed in FIG. 1. Suchrotation of the pawl 6, due to its involute configuration, will causethe pawl to grippingly engage the banding material 34, the grippingaction being between the pawl 6 and a platform-like portion 38 of thecarrier 4. Thus, movement of the piston 3 away from its left hand endposition as viewed in FIG. 1 will first cause the pawl 6 to be rotatedso as to grippingly engage the banding material 34 and thereaftermovement of the piston 3 moves the connecting rod 7 which in turn willcause the carrier 4, together with the pawl 6 to be axially moved alongthe tie rod 5, thus applying a tractive force to the banding material34. It will be appreciated that the gripping is effected during rotationof the cam 6 and the actual tensioning of the banding material 34 issubsequently produced by translation of the pivot pin 9. The distinctionbetween the gripping and tensioning functions is enabled by ensuringthat the piston 3, when commencing movement from its left hand position,can move through a predetermined amount before the carrier 4 is movedaway from the abutment 36. The instant at which the carrier 4 moves awayfrom the abutment 36 is the transistion instant between the gripping andtensioning functions.

Since the pawl 6 is in etfect a simple lever, the gripping force on thebanding material 34 is proportional to the applied power pressure andthus the resultant tension in the banding material is similarlyproportional. By making the cam face of the pawl 6 of involuteconfiguration, a constant leverage action is obtained, irrespective ofthe thickness of the banding material.

If 'the piston 3 completes its full travel before the desired tension inthe banding material is achieved, then the pressure medium behind thepiston 3 is expelled through a vent 39 in the body portion 1 of thehousing.

' Expulsion of the pressure medium in this way gives an audibleindication of incorrect tensioning.

Pressure medium is supplied to the device through a connection 17 in ahandle 27. The handle 27 carries a control valve retained by a grubscrew 24, the valve having a spool 15 and an operating button 16. Thespool has seals in the form of O-rings 30, 31 and 32 and is arranged forcontrolling pressure medium passages in known manner so that dependingon the way in which the valve is operated by means of the button 16,pressure medium can be applied to the left hand side of the piston 3 orthe space at the left hand side of the piston 3 can be vented to theoutside atmosphere.

In use of the device, the banding material 34 is passed around anarticle to be banded, and in such a way that the free end of the bandingmaterial 34 passes through the clip 33. The pusher plate 13 is thenengaged with the clip 33 and the valve is operated by means of thebutton 16 so that pressure medium is admitted to the space at the lefthand side of the piston 3. This causes movement of the piston 3, theinitial part of the movement being effective through the connecting rod7 for rotating the pawl 6 into gripping engagement with the bandingmaterial 34. Subsequent movement of the piston 3 then results in axialmovement of the carrier 4 and the consequent application of tension tothe banding material 34. When the desired tension in the bandingmaterial 34 has been achieved, the operating valve may be maintained inthe open position and it is then possible for the operator to continuewith any other necessary operations such as soldering or clinching theclip, while the banding device maintains tension in the bandingmaterial.

Release of the banding material subsequent to these operations iseffected by moving the operating valve into the closed position. Thisinterrupts the supply of pressure medium to the cylinder in which thepiston 3 is movable, and thence the said cylinder to the outsideatmosphere. The piston return springs 18 are then able to return thepiston 3 and the carrier 4 to their original positions, and during thisreturn action, the abutment surface 37 provided on the carrier 4 engagesagainst the abutment surface 36, thus arresting the carrier 4, continuedmovement of the piston 3 towards its left hand position thus resultingin anti-clockwise movement of the pawl 6 and consequent release of thebanding material 34 thereby.

It will be appreciated that the tension applied to the banding material34 depends on the extent to which the piston 3 is displaced in itscylinder subsequent to the banding material having been firmly grippedby the pawl 6. For enabling the tension in the banding material to beset at a desired value, a pressure controlling device, such as aconventional throttle valve V, may be provided in a pressure medium line40 between the banding device and the source of pressure medium. Such apressure controlling device may be of known construction and enables thepressure applied to the left hand side of the piston 3 to be maintainedat a predetermined adjustable value. In one known form of such apressure controlling device, a pressure gauge is provided whichregisters the pressure which the system has reached.

Irrespective of whether or not a pressure controlling device isprovided, the source of pressure medium may be an existing pressure lineor a foot pump or other pump. In order that the tension in the bandingmaterial is retained, non-return valve means should be provided forpreventing escape of pressure medium prior to fixing of the clip 33.Such non-return valve means would normally be provided in theabove-mentioned pressure controlling device.

It will be appreciated that the banding device of the invention enablesthe band or wire to be automatically gripped on the commencement oftensioning, and released after tensioning, this allowing easy insertionof the band or wire into the gripping mechanism. The arrangement of thegripping pawl 6 makes it possible for the gripping mechanism to grippurely by frictional action so that damage to the band or wire isavoided. This makes it possible for the band or wire to be drawn from acoil without wastage. Moreover, the lever action of the pawl 6 enablesdifferent widths and thicknesses of band or wire to be automaticallyaccommodated. Additionally, the construction is such that all movingparts are totally enclosed except for the insertion slots for the bandor wire, this making the device safe to the user, while at the same timeexcluding dirt.

I claim:

1. A device for tensioning an elongated banding material, comprising ahousing, a piston movably disposed in said housing, means for subjectingsaid piston to pressure fluid power, a carrier displaceable by saidpiston, a gripping member for said material, said gripping member beingcarried by said carrier, means connecting said piston to said grippingmember for actuating said gripping member into gripping engagement withsaid material said material said connecting means being so arranged thatsaid gripping member is actuated by the piston prior to movement of saidcarrier by the piston.

2. A device as defined in claim 1, comprising a connecting rod carriedby said piston and linked to said gripping member for moving saidcarrier after the actuation of said gripping member.

3. A device as defined in claim 2, wherein said gripping member is a campivoted on said carrier.

4. A device as defined in claim 3, wherein said cam has a grippingsurface of involute shape.

5. A device as claimed in claim 1, wherein said carrier has aplatform-like surface and said gripping member is arranged to grip thebanding material by cooperating with said platform-like surface.

6. A device as defined in claim 1, comprising a pressure medium lineleading to said tensioning device, and a pressure controlling device insaid line whereby to provide a controllable operating pressure for saidtensioning device which allows the tension in the banding material to bepredetermined.

7. A device as defined in claim 1, wherein a vent is provided in saidhousing and so positioned that it is uncovered by the pressure-impactedside of said piston when said piston reaches the extreme limit of itsworking stroke, but is not uncovered by the said side of said pistonduring a piston stroke corresponding to less than the full strokepossible.

References Cited UNITED STATES PATENTS 2,864,582 12/1958 Hall 254--513,090,599 5/1963 Weiss 254-51 3,173,456 3/1965 Bailey 254-5l X ROBERT C.RIORDON, Primary Examiner D. R. MELTON, Assistant Examiner U.S. Cl. X.R.93,2

